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AddiTion And SubTRACTion oF Time

example 1. Add 28 minutes 32 seconds and 24 minutes 42 seconds.

Solution. Write the times in columns correctly and then add.
Step 1. Add the seconds. min s
1
32 s + 42 s = 74 s = 60 s + 14 s = 1 min 14 s
28 32
Step 2. Add the minutes. + 24 42
1 min + 28 min + 24 min = 53 min 53 14

example 2. Add 16 hours 24 minutes 18 seconds and 31 hours 48 minutes 52 seconds.

Solution.

Step 1. Add the seconds.
18 s + 52 s = 70 s = 60 s + 10 s = 1 min 10 s h min s

Step 2. Add the minutes. 1 1
1 min + 24 min + 48 min = 73 min 16 24 18

= 60 min + 13 min = 1 h 13 min + 31 48 52
Step 3. Add the hours. 48 13 10

1 h + 16 h + 31 h = 48 h

example 3. Subtract 22 minutes 32 seconds from 30 minutes 18 seconds.
Solution. Write the times in columns correctly and then subtract.

Step 1. Subtract the seconds.

Since 18 < 32, regroup minutes and seconds. min s
29 78
So, 30 min 18 s = 29 min 60 s + 18 s = 29 min 78 s 30 18

Now, 78 s – 32 s = 46 s – 22 32
7 46
Step 2. Subtract the minutes. 29 min – 22 min = 7 min

example 4. Subtract:
a 4 hours 44 min from 6 hours 14 min b. 13 hours 28 min from 1 day
Solution. We write the measures of time in the appropriate columns and regroup to
subtract.

a. 6 h 14 min = 5 h 74 min b. 1 day = 24 h = 23 h 60 min
h min h min
5 74 23 60
6 14 24 00

– 4 44 – 13 28
1 30 10 32

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Time